A SOX concentration sensor for detecting a SOX concentration in exhaust gas is known. A normal SOX concentration sensor measures electromotive force produced when SOX changes into sulfuric acid ion within a solid electrolyte, in order to detect a SOX concentration in the exhaust gas. However, it is difficult for this SOX concentration sensor to detect an accurate SOX concentration when the SOX concentration in the exhaust gas is low.
A proposed detector for detecting sulfur components cannot detect an instantaneous SOX concentration but can detect an integrated amount of SOX passing through the exhaust passage during a given period (for example, refer to Japanese Unexamined Patent Publication No. 2008-175623).
The detector for detecting sulfur components comprises a SOX storage portion for storing SOX contained in the exhaust gas, measures a property such as electric resistance, volume or the like of the SOX storage portion, which changes according to the increase in an amount of SOX stored in the SOX storage portion and detects an integrated amount of SOX passing through the exhaust passage during a given period on the basis of the measured property.